Automobiles often include child locks for preventing doors, especially rear doors, from being opened from within the passenger compartment. Powered child locks typically require an actuator and a lockout control mechanism that is located on the door latch. The main problem with these types of locks is the lack of packaging space in the door to facilitate the actuator and the lockout mechanism. As the costs associated with a power child lock are high when compared to the value this feature adds to a vehicle, it is desirable to provide such a child lock at a minimum cost.
In addition, another desirable feature to include in a vehicle door latching or locking system is a “double lock”, wherein, when engaged, both the inside and outside release levers are simultaneously inactive. This feature has conventionally been incorporated into the design of the latch itself, which can often necessitate a very expensive redesign of a pre-existing latch. Since the functions of a child lock and a “double lock” feature are quite similar, it would be desirable to provide a single structure that could provide both functions and thus further reduce costs.
One alternative to using power actuators is use a shape memory alloy (SMA) wire to toggle the locking feature. SMA wires have the ability to contract when supplied with an electric current, and can be used to engage or disengage the lock. However, these systems are not without their own drawbacks. For example, existing linear toggle mechanisms require too much travel, requiring considerable lengths of SMA wire (an expensive component). In addition, depending on the arrangement of the latch components, it can be difficult to supply electrical power to the shape memory actuator. Finally, rotation of the electrical wires in linear toggle mechanisms may cause premature failure of the mechanism, therefore there is high demands on those systems for durability and reliability.